1. Field of the Invention
The present invention relates to an optical element and an optical component using the same. More specifically, the invention relates to an optical element for reflecting transmitted light and, thereby, converting a light path and converging light, and an optical device using the same.
2. Description of the Background Art
An optical transceiver 11 in the prior art is explained in reference to FIGS. 1A and 1B. FIG. 1A shows a cross sectional view of a conventional optical transceiver 11, while FIG. 1B shows an enlarged view of the light receiving system thereof viewed from the direction A. Dotted lines in FIGS. 1A and 1B show light paths. In this optical transceiver 11, as shown in FIG. 1A, light ejected from a light projecting element 5 is converged by a lens 18. Thereafter, the light path thereof is bent by about 90 degrees by inclined surfaces of a triangular prism 17, and is combined onto the end surface of an optical fiber 4. Light L ejected from the optical fiber 4 penetrates into a light guide portion 20 and is received by a light receiving element 6.
At present, in the art of optical communications, there is a demand for high communication speed, and along with this demand, there is another demand for compact size of a light receiving element in an optical transceiver. However, in this optical transceiver 11, wherein an optical element of a light receiving system arranged between the light receiving element 6 and the optical fiber 4 does not converge light, light L ejected from the optical fiber 4 will spread as shown in FIG. 1B. Therefore, if the size of the light receiving element 6 is made small, the loss of light L will become large. And, in this optical transceiver 11 of such a structure, because the light receiving surface of the light receiving element 6 faces the direction of the optical fiber 4, light ejected from the light projecting element 5 and reflected by the end surface of the optical fiber 4 will be received as returned light by the light receiving element 6, causing cross talk. This has been a problem in the prior art.
When light ejected from the light projecting element 5 is to be guided to the optical fiber 4, or light going out from the optical fiber 4 is to be guided to the light receiving element 6, if a light path is converted (deflected) and an optical element for converging light is used, light receiving efficiency may be increased. As an example of such an optical element, a light path converting element 1 is explained in reference to FIGS. 2A and 2B. FIG. 2A shows a perspective view of the light path converting element 1, while FIG. 2B shows a top view of a channel type curved wave guide 10 whose cross section area varies with the incoming surface S1 and the outgoing surface S2 thereof, and also shows light behaviors in the curved wave guide 10. In this light path converting element 1, a curved wave guide 10 made of a transparent resin is formed on the upper surface of a substrate 8. When light L going through the optical fiber 4 comes from the incoming surface S1 into the wave guide 10, light L that goes into the curved wave guide 10 repeats full reflection on the upper and lower surfaces and left and right side surfaces of the curved wave guide 10 and goes through the curved wave guide 10. Light L ejected from the outgoing surface S2 of the curved wave guide 10 is received by the light receiving element 6 that is arranged to face the outgoing surface S2. Therefore, the transmitting direction of the light L going through the curved wave guide 10 is bent by the curve of the curved wave guide 10. Because the area of the outgoing surface S2 of the curved wave guide 10 is made smaller than that of the incoming surface S1, light L ejected from the outgoing surface S2 of the curved wave guide 10 is converged, and is received efficiently by the light receiving element 6 with a small light receiving area.
However, in such a curved wave guide 10, in the case wherein the area of the incoming surface S1 is not equal to that of the outgoing surface S2, the curvature at the external circumferential surface will become large. Therefore, as shown in FIG. 2B, light going through the inside of the wave guide 10 leaks out from the external circumferential surface of the curved wave guide 10, causing lost light L′, and light transmitting efficiency will be deteriorated. Therefore, in cases involving converting a light path in an optical fiber 4 of the same diameter or so, it was possible to make crosssectional areas of a wave guide uniform and there was no problem. However, in cases involving converging light L ejected from the optical fiber 4 and receive light by the light receiving element 6 of a small light receiving area, light transmitting loss would become large. As a result, such a conventional curved wave guide appeared inconvenient. This has been another problem in the prior art.